1. Field of the Invention
The present invention relates to a soft X-ray microscope, and more particularly, to a soft X-ray microscope that uses a liquid target that is not affected by target fragments and that has excellent monochromaticity so that the soft X-ray microscope can be easily used in a laboratory and has spatial resolution of no more than 100 nm.
2. Description of the Related Art
In general, a microscope refers to an apparatus for enlarging a minute part of an object (hereinafter, referred to as a sample) to observe the minute part and may include an electronic microscope that uses electrons as a light source or an optical microscope that uses visible rays as a light source.
In the case of the electronic microscope, since the sample must be put under vacuum and must be physically and chemically pre-processed, it is not possible to observe a living sample such as the cells of an organism. In the case of the optical microscope, it is possible to observe a living sample; however, since the visible rays are used as the light source, the resolution is limited to about 200 nm due to the diffraction limitation of the light source according to the current technology.
Recently, a soft X-ray microscope using an X-ray wavelength region referred to as window of water (λ=2.3 to 4.4 nm) has been studied. In the region of the window of water, since there exists large X-ray absorption differences between water and protein that constitutes the living sample, it is possible to observe protein through a water layer of a thickness of several microns and to observe the inside of the living sample due to the permeability of X-ray.
The above-described soft X-ray microscope includes a light source chamber in which a solid target made of tantalum is provided, a light source for focusing pulse light on the solid target to generate X-ray so that the X-ray is radiated onto the living sample, a sample chamber in which the living sample is provided, a mirror chamber for leading the X-ray that transmits the sample to capturing device, and the capturing device for capturing the X-ray image that is scattered by the living sample or that transmits the living sample.
The operation of the soft X-ray microscope having the above structure will be described as follows. When the pulse light is emitted from the light source to the solid target, the pulse light collides with the target to generate a predetermined X-ray. The generated X-ray is radiated onto the living sample provided in the sample chamber to be scattered by the living sample and to transmit the image of the living sample. The capturing device captures the light that is scattered by the living sample and that transmits the image of the living sample so that the living sample can be observed.
However, since the target onto which the pulse light is radiated is solid, minute pieces are generated in the part onto which the pulse light is radiated and the generated pieces are attached to the internal surface of the light source chamber that remains vacuous in which the solid target is provided so that the vacuum degree is damaged. In particular, the pieces attached to the internal surface of the light source chamber prevent the X-ray from being precisely generated so that it is difficult to repeatedly use the soft X-ray microscope for a long time.
Furthermore, the solid target damaged by the radiation of the pulse light must be frequently exchanged in order to precisely generate the X-ray so that the light source chamber in which the solid target is provided must be released and reset under vacuum. Therefore, work time and maintenance and repair expenses increase.
The mirror chamber that leads the X-ray generated by the light source chamber to pass through the living sample includes mirrors on both sides of the living sample, that is, an illuminating mirror for illuminating the living sample before the pulse light passes through the living sample and an amplifying mirror for enlarging and amplifying the light that passed through the living sample illuminated by the illuminating mirror by the capturing device. The X-ray generated by the light source chamber is illuminated and enlarged by the mirrors and passes through the living sample and the capturing device captures the X-ray image to obtain an image.
However, in the above case, in order to enlarge and photograph the light that passed through the living sample by the capturing device in accordance with the optical enlargement magnification formula, the distance between the sample chamber and the capturing device is 3 to 4 m on the average, the magnification is about 286, and resolution is about 200 nm, which is similar to the resolution of the optical microscope.
As described above, the soft X-ray microscope in which the distance between the sample chamber and the capturing device is 3 to 4 m on the average in order to obtain an image of high magnification as mentioned above is preferably horizontally installed rather than vertically installed so that the use area of the soft X-ray microscope increases and that the space efficiency of a work place deteriorates.
Therefore, a work place for the exclusive use of the soft X-ray microscope must be additionally provided, which causes inconvenience and inefficiency.